CENTENNIAL, Colo. (Reuters) - Attorneys for accused Colorado theater gunman James Holmes, who could be sentenced to death if convicted of murdering 12 moviegoers last year, on Wednesday renewed their bid to bar key evidence from his upcoming trial.

In the latest in a series of pre-trial hearings, Holmes' defense team argued that searches of the onetime neuroscience graduate student's car and computers in the wake of the July 2012 massacre were improper.

A search warrant authorizing the seizure of all information from computers, thumb drives and other computer-related items belonging to Holmes was "unconstitutionally overbroad," defense lawyer Kristen Nelson said.

"What they cannot do is a broad sweep of personal information and then allow law enforcement to sift through them at their whim," she said.

But homicide Detective Tom Sobieski, who drafted the search warrant affidavit, testified that mass shooters frequently left an electronic trail, and investigators needed access to the devices to gather evidence.

Holmes, 25, has pleaded not guilty by reason of insanity to multiple counts of first-degree murder and attempted murder for opening fire inside a suburban Denver cinema during a viewing of the Batman film "The Dark Knight Rises."

His lawyers have said in court filings that their client was in the midst of a psychotic episode when he went on the shooting rampage, which also left 70 others wounded or injured.

Prosecutors are seeking the death penalty for Holmes.

As he has in most of his court appearances, Holmes sat impassively at the defense table and showed no emotion during the proceedings on Wednesday.

Public defenders also argued that shortly after the massacre, police improperly made an initial search of the California native's car, which was parked outside the crowded multiplex in Aurora, Colorado, without a warrant.

Police later found a handgun, ammunition, a ski mask and gloves inside the vehicle, but no bombs or explosives.

Prosecutor Karen Pearson countered that police had a suspected mass murderer in custody who was armed and clad in body armor, had deployed tear gas in the theater, and had told officers that his apartment was rigged with explosives.

"This was a fast-developing situation," she said, adding that it would be an "absurd result" if evidence was tossed out when public and officer safety were at risk.

Arapahoe County District Court Judge Carlos Samour Jr. has not ruled on the bulk of the suppression motions filed by the defense. The murder trial is scheduled to begin in early February, and could take up to eight months.